1. Field of the Invention
The invention relates to a method for transmission of a data signal on a line pair, and to a method for reception of the data signal.
2. Description of the Related Art
The invention relates to a method for transmission of a data signal on a line pair, and to a method for reception of the data signal. The invention also relates to a transmission circuit for transmission of a data signal via a line pair, and to a reception circuit for reception of the data signal.
By way of example, the transmission of data to the memory circuit and from the memory circuit in present-day dynamic random access memory (DRAM) memory circuits represents the greatest bottleneck for data in computer systems, since the data transmission rates are not adequate for the data requirement of a CPU. In order to solve the problem of a restricted data transmission rate between a memory module and, for example, a memory controller which is driving it, synchronous DRAM memory circuits were initially used, in which the data was transmitted in synchronism with the a clock signal. In consequence, the data rates could be increased from the previous 50 MHz to about 133 MHz. Next, double data rate (DDR) interfaces were introduced, and raised the transmission rates to the region of 400 MHz. DDR 2 technology (approximately 533 MHz) is currently being introduced to the market. In the meantime, however, the processing speed of the processors has also increased considerably, so that the gap between the data requirement for the processor and the data rate at which data can be transmitted from and to the memory module has in fact increased rather than decreased.
In order to increase the data rates, the transmission frequency must be increased, so that the signal transmission is more sensitive to external interference, and is thus less reliable. In consequence, synchronous transmission of data is still difficult. In particular, the synchronization of the data to a data bus to which the memory module is connected to one or more clock signals is problematic owing to the different signal delay times on the bus lines, as the transmission frequency increases.
At higher transmission frequencies, the data signals are also more susceptible to interference and influence one another, in particular by signal crosstalk.